Process for roasting sulfid ores.



U. W. RENWIGK. rnocxss FOR ROASTING SULPID oars.

APPLICATION FILED MAY 14, 1910. I 981,880 Patented Jan. 17, 1911.

2 SHEETSSHEBT 1.

G. W. RENWIGK.

PROCESS FOR ROASTING SULFID ORES.

' APPLICATION FILED MAY 14, 1910. 9 1, 0, Patented Jan. 17,1911.

2 SHEETSSHEET 2.

CHARLES W. IRENWICK, 6F ISABELLA, TENNESSEE.

PROCESS FOR ROASTING SULFID ORES.

Specification of Letters Patent.

Patented Jan. 17, 1911.-

Application filed May 14, 1910. Serial no. 561,276.

To all wlwm *it may concern:

Be it known that I, CHARLES W. BEN- wIoK, of Isabella, in the county ofPolk and fed'into a roasting furnace at the top and caused to pass downthrough several heated ovens or hearths to the bottom hearth from whichit passes out of the furnace; and, the air or oxygen is admitted at thebottom ovens and caused to pass up through the several ovens to the topone and out through a stack connected therewith. All metallic sulfidores are .thus roasted to oxids,. and, as is Well known, metallic oxidsact as catalytic agents and in this case S0 is thereby converted intoS0,. The heat of such furnace is produced by the burning of oil or othersuitable fuel and the upper hearths are hottest. As the ore travelsdownward and the S0 and other sulfurous gases pass upwar through thefurnace the most limited catalysis is produced.

It is the object of my improvement to reverse the current of the gasesand cause the same'to travel from the top oven down with the ore inorder to carry the high temperature found in the top ovens down to thelower ovens for the better roasting of the ores and in order to have theS0 come in more frequent contact with} the metallic oxids so thatgreater quantities of SO will be converted into $0,. I I

I have attained this object in the roasting process hereinafterdescribed and claimed.

The accompanying drawings illustrate the preferred form of apparatusemployed by me for carrying said process into practical effect.

Figure 1 of said drawings is-a vertical central section of an ordinaryfurnace shell rovided with flues and dampers for reversmg thegcurrent ofgases in the furnace and Fig. a like section and shows rotary rakes inelevation for moving'the ore in the ovens, and other features additionalto those shown in Fig. 1.

Two vertical lines are provided, on opposite'sides of the furnace shell,one for drawing ofi all or a part of the gases from any or formingroasting hearths.

of the upper ovens and entering'them into the lower ovens, and one fordrawing olf all or a part of the gases, depending on the amount ofconversion desired, and carrying them to the place ofuse.

In the drawings 1 is the furnace shell, and 2 arched floors separatingthe roasting ovens The upper floor has an exit opening for a stack Cthrough which the gases pass to the place where they are to be used, anda feed 0 ening cv provided with a hopper E for fee ing the ore into thefurnace on the floor next below the top one. F rom' this the ore iscaused to pass on down through the floor openings 03, c, f, g, 7L, 2',by means of ordinary rotary rakes, going outof the furnace at openings iin the bottom floor. The rotary rakes comprise a vertical rotaryshaft 3extended up through central openings in the floors 2 and provided withradial arms 4 for each hearth, said arms carrying bladelike teeth ontheir under side adapted to scrape the floor and being set at an inclineto their path of travel so that said.teeth will either pull the ore tothe central openings or push it to the peripheral openings. The footofsaid shaft may be journaled in a cross piece and provided withoperating gear for slowly rotating the shaft to work the rakes. At itsupper end said shaft car'- ries an eccentric 5 which operates a scraper6 for stirring the ore in a box beneath the hopper E and over thefeeding opening 0 to prevent clogging of said opening.

The shell of the furnace is supported on piers or columns 7 and beneaththe openings z arehoppers 8 which are adapted to catch the cindered oreand conduct it to a spout for conveying it to the place of storage.These hoppers close the openings 2' and may have damper-ed openings 9(any well known damper device may be used) whereby communication of theopenings a may be out off from the outer atmosphere.- Air or oxygen canbe let in at the top through openin c or stack C and the shell wall isprovi ed with air openings in each of the-ovens having dampersF forcontrolling the supply of air or oxygen for combustion. The air oroxygen and gases enter at the bottom through openings 2' and pass, asindicated by arrows 8 up through openings h g e d and then oiit throughthe stack G indie ii the furnace is working according to the ordinaryprocess.

The reversal of the current of gases is effected by means of fiues A andB placed at opposite sides of the furnace body andhaving branches at I)provided with dampers D which communicate through openings in thefurnace shell with the several ovens between the floors 2 so that whenthe damper D in stack 0 is closed the gases can be taken from any of theupper ovens and entered into lower ovens and can be passed into flue B,or can circulate up in the ordinary way after subjecting the desiredquantity of S0 to catalytic action, the damper in the stack 0 beingopened for'this purpose. By closing the dampered openings and all of'thedampers D except the one in the lowermost branch flue b the entire draftwill be downward in the furnace shell and through the D in the branchflues a b all or a part o the gases can be taken from any oft-he floorsthrough the flue B, depending on the amount of conversion desired. Allor a part of the gases may be drawn ofi from any of the upper floors,and turned down through flue A as indicated by arrows o to any of thelower floors and carried over to the flue B as indicated by arrows Z,the dampers D being opened in the branch flues a b at the point orpoints where it is desired the gases shall pass out of certain of theovens and into certain other of them and thence on to the fiue B orstack Cas desired.

The new roasting process consists in reversing the current of gases inthe manner described in order to increase the temperature at the bottomof the furnace and to cause the S0 in the furnace to come into morefrequent contact with the metallic oxids; The increase of temperature atthe bottom is very valuable in the roasting of the ores for the reasonthat the last traces of sulfur are hardest to remove and the hightemperature is thereby brought into contact with the ore 'on the lowerhearths and completely oxidizes the same Without any extra cost. The oreon the lower hearth is so heated that all sulfates are broken up and -asweet roast is obtained. These things have not been heretofore attained,so far as I am aware, by any single operation, but resort has alwaysbeen had to separate and distinct operations 7 for their accomplishment.

Extending the travel of the gases. in the roasting furnace by reversingthe current of their travel and causing the same to be downward with theore for a portion ofthe time is Very valuable, in the manufacture ofsulfuric acid for the reason that it greatly increases the frequency ofcontact ofv SO with the hot metallic oxids and greatly increases thequantity of SO that is converted into $0,. This greatly reduces the costof producing sulfuric acid. The reversing of the current of the gasescauses the dust to settle in the ovens and pass off with the ore, sothat the S0 passing inv the lines B C to the place of. use is much morefree from dust than when roasted in the ordinary way.

What I claim is:

1. The improved process for roasting metallic sulfid ores, whichconsists in passing the ores downward through a series of hot roastingovens, introducin air or oxygen into the lowermost of sai series ofovens and causing it to pass upward through said 1 ovens to theuppermost one of them, androasting metallic sulfid ores which consists:

first in subjecting a moving mass of such ores to the action of acurrent of hot air, or oxygen, and sulfurous gas having movement in adirection contrary to the movement of the ore, and second, subjectingsaid mass of movmg ore to the action of a current of hot air, or oxygen,and sulfurous gas having movement in a direction the same as that ofsaid ore, substantially as and for the purposes specified.

c. w. RENWICK.

Witnesses:

' V G. B. Fuuss, W. L. HEINz.

